Dielectric structure having lower-k and higher-k materials

Abstract

An electronic device including in any sequence: (a) a semiconductor layer; and (b) a dielectric structure comprising a lower-k dielectric polymer and a higher-k dielectric polymer, wherein the lower-k dielectric polymer is in a lower concentration than the higher-k dielectric polymer in a region of the dielectric structure closest to the semiconductor layer.

The invention claimed is: 
     
       1. A top gate thin film transistor comprising:
 (a) a substrate; 
 (b) a gate electrode; 
 (c) a semiconductor layer; and 
 (d) a dielectric structure comprising a lower-k dielectric polymer and a higher-k dielectric polymer; 
 wherein the semiconductor layer contacts the substrate; 
 wherein the dielectric structure is between the gate electrode and the semiconductor layer; and 
 wherein the lower-k dielectric polymer is in a lower concentration than the higher-k dielectric polymer in a region of the dielectric structure closest to the semiconductor layer. 
 
     
     
       2. The thin film transistor of  claim 1 , wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to 0% and the higher-k dielectric polymer is at a concentration ranging from about 60% to 100% of the total weight of the lower-k and the higher-k dielectric polymers in the region of the dielectric structure closest to the layer comprising the semiconductor. 
     
     
       3. The thin film transistor of  claim 1 , wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to about 10% and the higher-k dielectric polymer is at a concentration ranging from about 60% to about 90% of the total weight of the lower-k and the higher-k dielectric polymers in the region of the dielectric structure closest to the layer comprising the semiconductor. 
     
     
       4. The thin film transistor of  claim 1  wherein the lower-k dielectric polymer has a dielectric constant of less than 4.0. 
     
     
       5. The thin film transistor of  claim 1 , wherein the higher-k dielectric polymer has a dielectric constant of 4.0 or more. 
     
     
       6. The thin film transistor of  claim 1 , wherein the dielectric structure further comprises an interfacial layer. 
     
     
       7. The thin film transistor of  claim 1 , wherein the dielectric structure is a phase separated dielectric structure. 
     
     
       8. A top gate thin film transistor comprising:
 (a) a substrate; 
 (b) a gate electrode; 
 (c) an organic semiconductor layer; and 
 (d) a dielectric structure comprising a lower-k dielectric polymer and a higher-k dielectric polymer, 
 wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to 0% and the higher-k dielectric polymer is at a concentration ranging from about 60% to 100% of the total weight of the lower-k and the higher-k dielectric polymers in a region of the dielectric structure closest to the semiconductor layer. 
 
     
     
       9. The electronic device of  claim 8 , wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to about 10% and the higher-k dielectric polymer is at a concentration ranging from about 60% to about 90% of the total weight of the lower-k and the higher-k dielectric polymers in the region of the dielectric structure closest to the layer comprising the semiconductor. 
     
     
       10. The electronic device of  claim 8 , wherein the lower-k dielectric polymer has a dielectric constant of less than 4.0. 
     
     
       11. The electronic device of  claim 8 , wherein the higher-k dielectric polymer has a dielectric constant of 4.0 or more. 
     
     
       12. The electronic device of  claim 8 , wherein the dielectric structure is a phase-separated polymer blend. 
     
     
       13. A top gate thin film transistor:
 (a) a substrate; 
 (b) a gate electrode; 
 (c) a semiconductor layer; and 
 (d) a gate dielectric comprising a lower-k dielectric polymer-majority/higher-k dielectric polymer-minority first phase and a higher-k dielectric polymer-majority/lower-k dielectric polymer-minority second phase, wherein the first phase is located in a region of the dielectric structure closest to the semiconductor layer. 
 
     
     
       14. The thin film transistor of  claim 13 , wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to 0% and the higher-k dielectric polymer is at a concentration ranging from about 60% to 100% of the total weight of the lower-k and the higher-k dielectric polymers in the first phase. 
     
     
       15. The thin film transistor of  claim 13 , wherein the lower-k dielectric polymer is at a concentration ranging from about 40% to about 10% and the higher-k dielectric polymer is at a concentration ranging from about 60% to about 90% of the total weight of the lower-k and the higher-k dielectric polymers in the first phase. 
     
     
       16. The thin film transistor of  claim 13 , wherein the lower-k dielectric polymer has a dielectric constant of less than 4.0. 
     
     
       17. The thin film transistor of  claim 13 , wherein the higher-k dielectric polymer has a dielectric constant of 4.0 or more. 
     
     
       18. The thin film transistor of  claim 13 , wherein the lower-k dielectric polymer and the higher-k dielectric polymer are crosslinked. 
     
     
       19. The thin film transistor of  claim 13 , wherein the lower-k dielectric polymer is selected from the group consisting of polystyrene, poly(4-methylstyrene), poly(chlorostyrene), poly(α-methylstyrene), polysiloxane including poly(dimethyl siloxane) and poly(diphenyl siloxane), polysilsesquioxane, poly(methyl silsisquioxane), and poly(phenyl silsesquioxane), polyphenylene, poly(1,3-butadiene), poly(α-vinylnaphtalene), polypropylene, polyisoprene, polyisobutylene, polyethylene, poly(4-methyl-1-pentene), poly(p-xylene), poly(cyclohexyl methacrylate), poly (propylmethacrylPOSS-co-methylmethacrylate), poly(propylmethacrylPOSS-co-styrene), poly(styrylPOSS-co-styrene), poly(vinyl cinnamate), and mixtures thereof.